Slide valve controlled four-stroke cycle internal combustion engine



Feb. 15, 1.938. A; BUCH] 2,198,365 SLIDE VALVE CONTROLLED FOUR-STROKE CYCLE I NTERNAL'COMBUSTION ENGINE Filed March 5, 193e 2 sheets-sheet 1 A. BUCH! 2,108,365

STROKE CYCLE. INTERNAL COMBUSTION- ENGINE F65. v15, 193s.

SLIDE VALVE CONTROLLED FOUR 2 Sheets-Sheet 2 Filed March-5, 1936 Patented Feb. 15, 1938 SLIDE VALVE l(`}()1 \IT'R,OLLED FOUR-STROKE CYCLE INTERNAL COMIBUSTION ENGINE Alfred Biichi, Winterthur, switzerland Application March s, 1936, serial No. cassa In switzerland March 6, 1935 2 claims. (cl. 12s- 32) This invention relates to slide valve vcontrolled four stroke cycle internal 'combustion engines.

The invention is particularly concerned with the construction of such engines that are sup- 5 plied with precompressed charge and the working cylinders of which are scavenged.

The invention consists in shapingthe wall .por-

tions of the cylinder space that guide the entering charge and the scavenging air, in such manner, that the charge and the scavenging air are each directed at least during the end portion of the upstroke of the piston tangentially of the exterior circumference of the Vcombustion limiting wall portions of the lcylinder space acl,-` joining the exhaust ports forthel spent gases;

being so shaped that the flow of gas passing out through the' teatral. parties Qf the combustion chamber is `guided'"toi'vvard's the exhaust ports in a way as not to be disturbed by the entering charge.. e

'I'he flow of the entering and discharging gases may advantageously be improved by appropriately directing the ports in the valve slide and correspondingly shaping the portion of the cylinder guiding the ow at the entrance and at 5 the exit. 'Ihe ilowof the entering charge may be guided by conically slanting the end surface of the piston towards the combustion chamber, whereas the ow of the 'discharging exhaust gases and scavenging air respectively is con- 40 trolled, sov as not to be disturbed by the flow arriving through the entrance, principally by recesses or the like in the piston that'are shaped conformably to the direction of rotationl of the discharging low.

clearance spacebetween the piston and the cylinder end beyo: .d the combustion chamber, raised portions are provided on the end surface of the cylinder opposite the recessed points of the pis- 50 ton, so that a minimum permissible clearance between these parts is obtained. It will be understood that the amount of this clearance is so chosen at the points where the charge enters and at the points of discharge of the exhaust gases that` but small resistances, i. e., losses of Furthermore, in order to avoid increasing the drive of the sleeve valve, and

pressure and velocity accrue, in the flow. of the entering charge and the flow of the discharging exhaust gases.

In the accompanying drawings two embodi- 'ments' of the invention are schematically illus-V trated by way of example only, in which Fig. 1 shows. a vfragmentary section through the upper portion of a working cylinder and the associated piston of an internal combustion engine to which the `invention is applied;

Fig. 2 shows a section along ltheline II-II of Fig. 1;

Fig. 3 is a sectional perspective view showing Y the outer end surface of the piston, the section being ltaken through the port openings of 'the cylinder and of the sleeve valve;

Fig. 4 shows a section similar to Fig. 1 in which i the movements of flow of the charge and of the scavenging air respectively past the piston and' through the combustion chamber in the cylinder end wall are indicated;

Fig. 5 shows a fragmentary section through the upper portion of a working cylinder and the associated piston of a second constructional form of an internal combustion engine to which the .invention is applied Fig. 6 shows a section along the lile VI-VI in Fig. 5;

Fig. '7 is a sectional perspective view of the upper endl of the piston with the combustion chamber depressed therein, the section being taken through theports of the sleeve yvalve of the engine;

Fig. 8 shows a section similar to Fig. 4 in which the movements o'f ow of the charge and of the scavenging air respectively past the cylinder end Wall and through the combustion chamber in the piston are indicated; v

v Fig. 9 represents a sectional end elevation of an internal combustion engine, as illustrated in the Figs. 1 to 4, the section'being taken through one of the working cylinders thereof;

Fig. 10 shows a side elevation of the engines as illustrated in thel Figs. 1 to 4 and the Figs. 5 to 8;

Fig. 11 shows a transverse vertical section `taken completely through the engine illustrated Fig. 12 shows a section on the line XII-l-,XII in rig. y11.

through the axis of one of its workingcylinders shows thev piston to assume its extreme outer end position. Fig. 4 shows the piston to occupy a different position from that shown in Fig. 1, namely, shortly before arriving at its outer dead centre or after having moved out of the same a small extent. 'I'he Figs. 1 to 4 show in fact all positions of the piston in which scavenging of the cylinder and particularly -of the combustion chamber takes place. To this end the intake and exhaust ports of the sleeve valve are each shown in open condition in all of these gures.

I designates the working cylinder, 2 the operating piston, 3 a cylindric sleeve valve encompassing the piston 2 and controlling the entrance of the chargeD and the discharge of the exhaust gases. 4 represents the end portion of the cylinder which in this case includes the combustion chamber in depressed position. 'I'he entering charge passes through a passage 6 into'intake ports 1 ahead of the sleeve valve 3, and through corresponding ports 8 in the valve 3 into the working cylinder I. The ports 8 are obliquely directed so as to impart to the entering4 charge a rotational movement of flow about the cylinder axis as indicated by the arrows a.

According to the invention, in the end surface of the piston 2 a recess 8 is provided. This recess extends only over that portion of the circumference where intake ports 8 are situated, the limiting walls of which being so directed that they impart to the entering charge, a movement of flow tangentially of the periphery I of the restricted combustion chamber 5, when the piston is positioned in the vicinity of its outer dead centre position. Furthermore, the end surface of the piston 2 and the oppositelydisposed wall portions of the cylinder end portion 4 are so inclined, that the entering charge and the scavenging air respectively are guided to surely'pass into the restricted combustion chamber instead of into the larger cylinder space underneath as longas the piston assists in this guidance.

The charge is then deflected by the peripheral wall Ill of the restricted combustion space to pass on in a helical movement of ilow (Fig. 4) up to the end wall II of the combustion chamber 5 most remote from the piston, as indicated by the arrowsb, to return therefrom substantially through the central portion of the combustion chamber back to the piston whlle still maintaining its rotational movement of flow, as indicated by the arrows c.- l

In the end surface of the piston 2 a further recess I2 is arranged which receives the gases leaving the central portion ofthe combustion 'chamber 5 to, guide them towards the -exhaust vantageously, also so shaped that the rotational V ports I3'of the sleeve valve 3. This recess is, ad-

movement oi now, as indicated by the arrows dn which was initiated on the entrance side, is maintained. Also the exhaust ports I3 of the sleeve valve 3 are advantageously shaped conformably to this" movement.- The latter parts pass on the exhaust gases -to the exhaust ports I4 in` the cylinder I from where they areffurther removed. y

The end portion 4 of. the cylinder is so shaped piston that at all the respective surface portionsA but a. minimum permissible clearance space I5 is left. 'Ihe end portion of the cylinder thus con- '9, but may, if desired, .be effected fines the piston end, advantageously. as completely as possible.

In Fig. 5 a vertical section through the axis Y of the combustion chamber of the second constructional example of the internal c'ombustion engine, according to the invention, is shown.

Fig. 8 shows the piston of this constructional example in a position somewhat spaced from the dead centre position. This constructional example, which is represented in the Figs. 5 to 8 differs from that shown in the Figs. 1 to 4 by the restricted combustion chamber being depressed in the piston 2 of the engine. The peripheral portion of the piston end surface slants radially inwardly conformably to the corresponding portion of the inner surface of the cylinder end portion 4. The entering charge passes into the restricted combustion chamber 5' in the direction of the' arrows a. Since the charge impinges thereat in a-tangential and downwardly inclined direction, it thereupon assumes a helical downwardly directed movement of flow b, as clearly shown in Fig. 8, to subsequently impinge on the bottom I I' of the combustion chamber and then, by continuing to turn in the, same direction, forms inner helical return convolutions c back Ito the cylinder end portion to pass to the exhaust'ports I3 in the sleevevalve 3 and the exhaust ports I4, as indicated by the arrows d. The end surface of the piston and the surface of the cylinder end portion 4 overlying the same are, in this case also, so shaped that inthe -dead centre position only a minimum clearance I5 exists between these two ports, as evident from Fig. 5. The chain dotted lines shown in this figure are for indicating the minimum amount of play left between the mating raised and recessed surface portions on the cylinder and piston ends respectively.

'I'he Figs. 9 and 10 represent an end and a side elevation respectively of an engine to which the invention is`applied. By I6 the internal combutsion engine as such is designated, whereas I1 refers to the exhaust driven machine and I8 to a charging and scavenging air blower. The exhaust gases pass out through the.V sleeve valves 3 to be admitted to the exhaust driven machine I'I through conduits I9 and are then led down--- wardly to escape at 20.

The charging and scavenging air, however, passes from the .blower I8 tothe entrance side of the'sleeve valve'3 through conduits 2| and'22. The sleeve valve 3 is shown in Fig. 9 to open only `into the exhaust conduit. 'I'he scavenging operation has not yet begun at this moment. "Ihe from a separate source of power. The internal combustion engine may be of anysuitable type. 'I'he drive of the sleeve valve is not shown in Fig.

in the same manner as shown in Fig. 11'.`

`In the Figs. 11 and 12 a constructional exampler voi the drive vof the sleeve valve is shown. Fig.

11 'represents a vertical section through the axis of the cylinder, whereasFig. 12 is a horizontal section through the lower end of thc slide valve. A pair of cranks 23 and 24, which is actuated from the main shaft 25'of the engine, imparts to the sleeve valve 3 a combined movement about the cylinder axis land longitudinally thereof at thesame time, by means of 'a connecting rod 38 and a guide stud 32 connected tb the latter by I means of a ball joint 3|, so thatthe sleeve valve Naturally anysuitable types of slide valves and c drives therefor may be employed. L

In Fig. Il, the valve slide 3 is shown in a position in which it does not open either the' exhaust or the intake ports. The piston forces during the end portion of its compression stroke the charge into the restricted combustion chamber in a direction tangentially of the latter and thus imparts to the charge an impulse of rotational movement shortly before the ignitionv takes place. h

By means of the invention it is possible to scavenge and supply respectively with fresh charging air the combustion chamber 5 l,or '5' of a slide valve controlled internal combustion enginel of the type described. The combustion chamber is thereby not only illled with fresh cold air, but in addition its walls are cooled interiorly: The jet of cold air arrives first at these hot walls and the air thus preheated then passes out through the central portion of the combustion chamber towards the exhaust ports.

Furthermore, by eiect of theV described irregularly lstepped oil shape o1' the piston, as regards the cylinder axis, once more a vigorous rotational movement of ow advancing in the'I direction of the cylinder axis is imparted to the content of the working cylinder in which way the air,

which is displaced laterally beyond the combustion chamber 5', is guided onto the periphery oi' the combustion chamber E', in a similar manner as during the charging andscavenging operation, and is imparted thereat a rotational movement of ow. By effect oi' this rotational movement oi flow of the combustion air advancing towards the entering fuel, which is admitted to the combustion chamber through one or more apertures 23, is divided in an improved manner, so that even with a minimum surplus amount of air, a still more perfect combustion than usual is obtained.

Various changes may be made from the embodiments of the invention, as shown. In any case it is, however, indispensable that the desired 'end through the passages 2l in known manner. It

will be observed that the invention can also be applied to internal combustion engines operating with artiilcial ignition. In this 4case it is, however, necessary vto provide that during the actual scavenging of the combustion chamber and the cylinder only pure air instead of a'mixturis introduced.

what I claim ist 1. In a four-stroke cycle slide valve controlled internal combustion engine, a working cylinder having a closed end, a working piston in said cylinder cooperating with saidv cylinder end with its adjacent end, one of said ends having an axially extending bore of less diameter than the cylinder and constituting a combustion chamber. a "slide valve in said cylinder surrounding said piston, said valve and cylinder having registerable intake and exhaust ports, and mating surface configurations on said cooperating piston and cylinder ends extending iro'm'the intake valve ports angularly around the piston and cylinder ends,

and inwardly to the combustion chamber, forming Vnear the top dead center position of said piston a guiding passage for the entering charge and scavenging air, which passage opens into the combustion chamber substantially tangentiallyl for producing a helical flow of Iluid into said chamber, said piston and cylinder ends alsohaving substantially mating channel-shaped surface conflgurations extending from a central portion of the combustion chamber outwardly to the exhaustports forming near the top dead cen-L yhaving a closed end, a working piston in saidcylinder cooperating with said cylinder end with its adjacent end', ,said cylinder end having an axially extending bore oi less diameter than the cylinder and constituting a combustion chamber, a cylindrical slide valve in said cylinder surrounding said piston, said valve and cylinder having registerable intake and exhaust ports, said piston having an axially projecting extension of less diameter than the piston mating with said bore of said cylinder, and mating surface configurations on said piston end and projecting extension and said cylinder end extending from the intake valve ports angular-lyr around the piston and cylinder ends, and inwardly to the combustion chamber, forming near the top dead center position ot said piston a guiding passage for the entering charge and scavenging air, which passage opens into the Acombustion chamber substantially tangentially for producing a helical ow of fluid into said chamber', said piston end and extension thereof and cylinder end also having mating surface coniigurations, comprising a recess formed in the central portion of the piston extension and a passage having outwardly diverging walls extending from said recess outwardly and axially to the exhaust ports, forming near the top dead center position of the piston an exhaust passage in contiguity -with said helical ilow, whereby the helical now of nula is reflected by the bottom of and bore axially of the combustion chamber to the exhaust passage and thence passes'to the exhaust valve mm' i A I Amm Biicm. 

